Costa et al.  provide possibly the most comprehensive survey of measurements used in complex networks analysis [Arxiv]. Starting from well known measures such as degree distribution, centrality, modularity etc., they move on to spectral measures and fractal dimensionality. (I am not sure what some of these measures are!) They finally discuss statistical methods for measurement selection, including Principal Component Analysis. I believe they are using PCA like analysis to select “features” of networks based on which they can classify them. If you are doing network analysis, I suggest you keep this survey handy.
 Luciano da F. Costa, Francisco A. Rodrigues, Gonzalo Travieso, P. R. Villas Boas. Characterization of complex networks: A survey of measurements. Advances in Physics, Volume 56, pages 167 – 242, Issue 1 (2007)